Cutting tool



Jan. 14, 1964 g, c s o s 3,117,366

' CUTTING TOOL Filed March 6, 1961 INVEN TOR. I

fow/A/ C. 0957012, 8/2. BY

United States Patent 3,117,366 CUTHNG TGUL Edwin C. Castor, r., 12.768Argyle, Southgate, Mich. Filed M. 6, 1961, Ser. No. 93,376 1 flaim.(ill. 29-l03) The present invention relates to a rotary metal cuttingtool, and more particularly to a rotary cutting tool in which thecutting teeth are formed with an improved chip-breaking grooveconstruction.

It has been known heretofore that the provision of chip-breaking goovesin the cutting edges of metal cutting tools will irnprove the operationof the tool. The chip-breaking construction embodied in the presentinvention is directed towards improving the operating characteristics ofsuch tools. The present desigri permits rapid stock removal with aminimum of chatter or vibration and also low heat built-up in the toolto result in increased tool life and reduced wear on the machine inwhich the tool is mounted.

It is an object of the invention to provide a rotarmetd cutting toolhaving chip-breaking grooves in the cutting teeth.

Another object of the invention is to provide chipbreaking grooveshaving a novel configuration which results in uniform chip-breaking tobalance the cutting tool and permit operation of the tool with low powercon sumption.

A further object of the invention is to provide chipbreaking grooves inthe cutting teeth of the tool which form individual teeth-portions onthe cutting teeth, each of such portions having a configuration whichresults in improved chip-breaking.

Another object of the invention is to provide a cutting tool in whichthe cutting teeth are for-med by helical flutes and the chip-breakinggrooves are formed by a continuous helical groove of the opposite handfrom the flutes to provide an efiicient chip-breaking action.

Other objects of this invention will appear in the following descriptionand appended claim, reference being had to the accompanying drawingsforming a part or" this specification wherein like reference charactersdesignate corresponding parts in the several views.

In the drawings:

FIGURE 1 is a view in perspective of one embodiment of the cutting toolof the present invention;

FIGURE 2 is a side elevatioual view of the cutting tooth portion of theFIGURE 1 tool;

FIGURE 3 is an end view of the FIGURE 1 cutting tool; and

FIGURE 4 is a sectional View taken substantially along the line 4-4 ofPlGURE 2 looking in the direction of the arrows.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in its application to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings, since the invention is capable of otherembodiments and of being practiced or carried out in various ways. Also,it is to be understood that the phraseology or terminology employedherein is for the purpose of description and not of limitation.

FIGURE 1 illustrates one embodiment of the rotary cutting tool of theinvention. The tool it is particularly adapted for use as an end mill onmilling machines of both the vertical and horizontal type. However, italso finds application in other machines such as boring mills anddie-sinking machines.

The tool 1% which has a generally cylindrical body,

is provided with a shank r12 having a flat M for securement of the toolto the tool-holding mechanism of a cut- Patented sFan. 14, 19%

ting machine. The tool is adapted to be rotated and fed axially into ametal body whereby the cutting end 16 will perform the initifl cuttingaction. The tool is then moved sideways whereby the helical cuttingteeth 20 will perform the cutting action.

The cutting portion of the tool is provided with a plurality of parallelhelical flutes 18 which define the plurality of parallel helical cuttingteeth 28*. As is conventional, the flutes are formed as a right-handhelix. The teeth 2th and flutes iii are formed according to conventionalpractice with respect to the radius at the bottom of the flutes, depthof flutes, width of flutes, clearance angle, number of flutes, anddegree of spiral of flutes. As will be noted in FIGURE 3 the cutting end16 is ground at 22 and 23 to give the desired cutting edge. As viewed inFIGURE 3, the tool is adapted to be rotated counterclockwise to performthe cutting actio'i.

Longitudinally spaced chip-breaking grooves 24- are provided in each ofthe teeth iii. The grooves 24 are formed during the fabrication of thetool before the tool is hardened. The grooves 24 form a pattern which isa continuous helical spiral around the circumference of the tool body.This helical spiral is of the opposite hand to that of the flutes 18.Thus, the grooves 24 form a left-handed helix. The spiral is also ofshorter lead than that of the flutes.

As will be noted, a tooth portion 26 having a cutting edge 3d is definedbetween each pair of adjacent grooves 24. The portions 26 are formed ina shape which assists in the chip-breaking action to provide the desiredoperating characteristics of the tool.

Referring to FIGURE 4, it will be seen that the depth of each tooth isrepresented by the letter A, the radius of the crest of each tooth isrepresented by the letter B, the radius at the bottom of the grooves 24is represented by the letter C, the center to center distance betweenthe root of adjacent teeth is represented by the letter D, and the angleblending t e crest with the bottom of the grooves is represented by theletter E. It has been found that for preferred results, these dimensionsare preferably in the relationship as shown in the following table ofexemplary tool sizes, the dimensions being given in inches:

A B C D E Depth Radius Radius Center Angle Diame er of Tooth Crest ofBottom to Center Blending of Body Tooth 0t Tooth Root of \Vith TeethCrest and Root Radii,

degrees 3- .070 070 .040 .170 5 .075 .075 .010 170 25 a. .075 .078 .010.170 25 .078 .078 .0i0 170 25 1 .000 .080 .040 .200 25 1% .085 .095 .010.200 25 1V .003 .000 .000 .220 1 .105 .105 .100 .250 25 2 .130 .120 .30025 2 .155 .140 .350 25 it will be additionally noted that each toothportion '26 has curved S-shaped side walls 2 3, 3% formed by the grooves24. The side walls 28, 3Q; define a tooth portion which is thicker atthe base 36 than at the crest 33. This results from the fact that thegrooves 24- are narrower at their bottoms 44 than at their top portions4t. relationship provides a groove configuration which efiectivelycaptures the chips as they are produced and turns each chip in a desiredcurvature to cause uniform breakage of the chips into uniform sizes.

In manufacturing the tool it cylindrical steel stock is first cut to thedesired tool length. The fluted end of the tool is then drilled andcountersunk as at 48 to permit holding of the tool for furtheroperations. The grooves 24- are then provided in the outer periphery ofthe tool in a continuous fashion by means of forming tools. The depth ofthis groove is approximately one-third of the ultimate depth of theflutes 18. The flutes 18 are then machined into the stock andform-relieved by providing flats 21 extending downwardly and rearwardlyfrom the cutting edges 34 to provide clearance. The flat 14 may bemachined into the shank 12 at this time. The tool is then subjected toheat treatment to provide the desired hardness and toughness for cuttingmetal. The shank. 12 is then rough and finish ground to .the desiredtolerance. The cutting edges 34 and bottom of flutes 18 are alsofinished ground and the end 16 is sharpened for use.

The resultant tool has been found in practice to be capable of removingmetal stock at a rate as much as five times that of conventional cuttingtools. This is accomplished with very little machine vibration andrelatively low tool temperatures. The present construction has theadvantage of rapid dissipation of heat to maintain such lowtemperatures. The reduction of tool chatter and machine vibrationresults in reduced cutting machine failure which saves, in addition tothe cost of mainte nance, the expense of having the machine remain idleduring repairs.

Having thus described my invention, I claim:

A rotary cutting tool comprising a generally cylindrical body, said bodyhaving a plurality of parallel helical flutes in its outer peripheryforming a plurality of parallel helical cutting teeth, the body diameterranging from a size of one-half inch to two and one-half inches, thedepth of the flutes ranging from .070 to .155 inch, said flute depthsincreasing in proportion to increase in body diameter, said body havinga helical groove in its outer periphery which extends to a depthsubstantially one-third the depth of the helical flutes; said helicalgroove being of the opposite hand and of shorter lead than the helicalflutes; said helical grooves forming a plurality of longitudinallyspaced chip-breaking grooves in each of the helical teeth; each of thetooth portions between a pair of adjacent chip-breaking grooves havingsubstantially symmetrical S-shaped curved side walls formed by thechipbreaking grooves; said side Walls defining a tooth portion which isthicker at the base than at the crest.

References Cited in the file of this patent UNITED STATES PATENTS1,307,525 Trebert r June 24, 1919 2,113,554 Johnson Apr. 5, 19382,855,657 Erhardt Oct. 14, 1958 FOREIGN PATENTS 8,725 Great Britain Apr.15, 1902 494,319 France May 26, 1919 438,354 Germany Dec. 13, 1926771,631 France July 30, 1934 439,799 Italy Sept. 28, 1948 672,117 GreatBritain May 14, 1952 319,309 Switzerland Feb. 15, 1957 1,230,614 FranceApr. 4, 1960 OTHER REFERENCES Article: Hydiaspeed Heavy-Duty MillingCutters from Machinery (British trade magazine), vol. 94 of Mar. 25,1959, pages 670 and 671 received in the Orfice Apr. 6, 1959.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3 ll7366 January 14L,1 1964 Edwin (2 Castor Sr.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 4 line 5, for "grooves" read groove '0 Signed and sealed this 9thday of June 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

